Our goal is to discover those processes involved in the transport of odorous substances to and away from the receptor sites on the olfactory sensory neurons. It appears that odors entering the vertebrate nose stimulate the release of secretory granules from sustentacular cells and modify the endogenous activity of cilia on the receptor cells. Responses of the cilia depend upon the developmental age of the cell from which they grow. The objectives of this study are to characterize the responses of the different cilia types, to determine the processes responsible for granule release and for odor-evoked changes in ciliary movement, and to find the relationships between these events and the resulting initiation of the neural message. We will determine the effects of induced changes in organelle activity including blockade of the secretory process and of ciliary motion on the sensory response measured electrophysiologically and behaviorally. The chemical properties of the granule material will be studied with respect to its affinity for odorous substances.